Method and apparatus for igniting underground formations



April 9, 1968 R. s. KIRK ETAL. 3,376,928

METHOD AND APPARATUS FOR IGNITNG UNDERGROUND FORMATIONS Filed July 2l, 1966 INVENTORS ROBERT S. K/RK K/ C. HONG BY usf,

United States Patent O 3,376,928 METHOD AND APPARATUS FOR IGNITING UNDERGROUND FORMATIONS Robert S. Kirk, Los Angeles, and Ki C. Hong, Fullerton, Calif., assignors to Chevron Research Company, San Francisco, Calif., a corporation of Delaware Filed July 21, 1966, Ser. No. 566,891 7 Claims. (Cl. 166-38) This invention relates to igniting petroleum-bearing formations penetrated by a Well; and, more particularly, this invention relates to an improved method and apparatus for heating an underground formation so that combustion may be started.

Underground combustion wherein a portion of the oil in an oil-bearing formation is burned to assist in producing an unburned portion of the oil has become a tool of the secondary recovery engineers. One problem still not completely solved concerns igniting the petroleum in the formation. Heretofore, ignition was accomplished using conventional tools, such as electric heaters and downhole gas-air burners. Other methods have been suggested, but none of these have been found entirely satisfactory.

The present invention is particularly directed to a selfcontained downhole igniter useful to ignite oil-bearing formations. The igniter preferably uses charcoal briquettes as fuel. The briquettes are ignited and burned to generate heat and raise the temperature of the formation above the ignition point. Air is injected to support cornbustion of lthe charcoal and to ignite the heated formation. The apparatus of the present invention is constructed in a manner to assure that ignition will result without overheating the well casing or liner which could cause the casing or liner to collapse. l

In one aspect, the downhole igniter comprises an outer elongated tubular member having both ends open. Refractory lines are provided on Ithe interior of a portion of the elongated tubular member and form a central ow path through the tubular member. The central ow path of the tubular member .is loaded with charcoal briquettes. Air bypass ports are formed in the elongated tubular member above the load of briquettes. Flow-restricting means on the tubular member above the bypass ports form a flowimpedance between the exterior of t-he elongated tubular member and Ithe interior of the well casing or liner so that a portion `of the air injected down the well will pass into the upper end of the elongated tubular member. Means for igniting the charcoal are carried in the upper end of the tubular member and means for suspending the burner in a well at a level suitable to ignite a formation are connected to the top of the tubular member.

It is an object of the present invention to provide a self-contained igniter for safely igniting an underground formation penetrated by a well. Other advantages and objects of the present invention will become apparent from the following detailed description read in light of the accompanying drawing, in which:

FIGURE 1 is an elevational view, partially in section, showing a preferred form of apparatus assembled in accordance with the present invention;

FIGURE 2 is an enlarged elevational view with parts broken away for clarity of presentation on showing the preferred form of apparatus assembled in accordance with the present invention;

FIGURE 3 is a sectional View taken at line 3-3 of FIGURE 2; and

FIGURE 4 is a sectional view taken at line 4-4 of FIGURE 2t.

Referring to the drawing and FIGURE l in particular, a preferred embodiment of the present invention is generally designated by the number 20. The igniter 20 is located adjacent the formation 22 which is to be ignited. A well 24 having casing 25 has been drilled from the surface of the earth and penetrates the formation to be ignited. The casing or liner 25 has a number of perforations 26 located adjacent the hydrocarbon-bearing formation 22. The igniter 20 is suspended in the well by suitable means, such as wire line 27. A wire line truck 28 having suitable apparatus for running wire line may be used to run the igniter in and out of the hole. Under some circumstances it may be desired to use a lubricator. A source 29 of air under pressure is connected to the well by means of pipe 30 and valve 31. The wire line 27 runs through stuling box 32 which prevents excessive air leakage out of the well.

In FIGURES 2, 3 and 4, the preferred embodiment of apparatus assembled in accordance with the present invention is shown in enlarged detail so that the present invention may be more readily described. An elongated tubular member 40 forms the main shell of the apparatus of the present invention. The tubular member 40 has a refractory lining 41 which forms a central ilow path through a major portion of the tubular member 40. The refractory lining 41 preferably is formed of tubular graphite having a wall thickness of at least 1/2 inch. Fuel means 42 are contained in the central ow path of the refractory tubular lining 41. The fuel means are arranged to allow for the passage of a substantial amount of air through the central flow path. Charcoal briquettes are the y preferred fuel. It has been found that the amount of heat released can be markedly improved by soaking the charcoal in oil. A preferred ratio found suitable for igniting petroleum formations comprises a rat-io of l pound of charcoal saturated with '1/2 pound of No. 5 white oil (or its equivalent) -per 1 foot interval of oilsand The charcoal is retained in the tubular member by means of retaining bar 43.

Bypass air ports 44 are fo-rmed in the upper portion of the tubular member 40 above the level of the charcoal 42. The bypass ports allow a substantial amount of air to bypass the interior central ow path of the tubular member and to flow down the annular chamber 45 formed between the exterior of the tubular member 40 and the interior of the casing 25. This bypass air prevents overheating of the casing 25 adjacent the portion of the tubular member containing theV fuel. A ow restricting means 46 is placed on the outside of the tubular member 40 above the bypass -ports 44 and above the top of the perforated portion of liner 25 to cause the major portion of the air coming down well 24 to flow into the upper open end of the tubular member 40. The port means are sized so as to bypass from 2 to 5 times the amount of air that flows through the charcoal 42 in the central flow passage. Table I shows the preferred ratios of injection air versus bypass air for dierent injection pressures.

TABLE I Injection Well Pressure, p.s.i.g. -*M

The igniter 20 is suspended in the well by means of wire line 27. Bail 47 connected to the upper end of tubular member 40 by pins 48 and 49 cooperating with the eyes in lugs 50 and 51 is used to hang the igniter. A pair of clevises 52 and 53 connected to either end of ignition case 54 serve to complete the connection with wireline 27.

In a preferred form, the ignition of the charcoal is accomplished by means of a Fenner grenade 60 located immediately adjacent the upper end of the charcoal load 42. The Fenner grenade is an incendiary device of a type well known in the art. Electric squib 61 and a thermit fuse 62 are used to ignite the grenade. Lead wires 63 and 64 extending from the ignition case 54 activate the squib. Located in the ignition box 54 are a battery 65 and a timing device 66. The timing device can be set for any desired time delay so that the igniter may be run to a desired level in the hole prior to the time ignition occurs.

Air at a rate of at least 150 standard cubic feet per minute ,should be injected into the well before the timing device activates squib 61. At least 70 standard cubic feet per minute should flow through the charcoal located in the central flow path of the tubular member 40. A substantial amount of the air injected into the well bypasses the central ow path and flows through annular chamber 45. The width of the annular chamber 45 should be from 1/2 inch to 3A of an inch. Thus the difference between tbe diameter of the tubular member and the diameter of the casing should be from l inch to 11/2 inches.

A particular example of a preferred embodiment of apparatus not intended to be restrictive but only as a guide is set out below. The igniter was designed for and used in a 6% inch O.D. casing by 5.761 inch I.D. slotted liner. The elongated tubular member was thin-walled carbon steel tubing having an outside diameter of 41/2 inches and au inside diameter of 41A inches. Graphite pipe was used to form the refractory lining for the steel tubular member. The graphite had a 4.184 inch outside diameter and a 2.937 inch inside diameter. Four bypass ports were formed above the level of the charcoal pack. The diameter of the bypass holes varied with the injection pressure used. Thus for injection pressures of from to 250 p.s.i.g., the diameter of each of the bypass holes was 1/2 inch. For pressures of between 250 p.s.i.g. to 500 p.s.i.g., 3A of an inch diameter 1bypass holes were used. The tubular member was 20 feet long, of which about 16 feet was packed `with charcoal. An asbestos packing band was used as the ow restricting means to insure that a major portion of the injected air was directed into the tubular member. The apparatus proved successful at pressures up to 500 p.s.i.g. For pressures above 500 p.s.i.g., the diameter of the air bypass holes should be increased.

Although only specic embodiments of the present invention have been described in detail, the invention is not to be limited to only such embodiments but rather by the scope of the appended claims.

We claim:

1. An apparatus for use in igniting an underground petroleum-bearing formation penetrated by a well, said apparatus comprising an outer tubular member, a refractory tubular lining on the interior of at least a substantial portion of said tubular member, said refractory lining forming a central flow 4path through said tubular member, fuel means contained in said central ow path adjacent the portion of said tubular member having said refractory tubular lining, said fuel means being arranged to allow the passage of a substantial amount of air therethrough, means on the lower end of said tubular member to retain said fuel means in said tubular member While allowing passage of air through the bottom end of said tubular member, port means formed in the upper portion of said tubular member above said fuel means providing communication between the central ilow path of said tubular member and the outside of said tubular member to provide bypass air to the outside of said tubular member, flow restriction means on the outside of said tubular member above said port means and adapted to form a flow impedance between the outside of said tubular member and a well casing to cause a substantial amount of air to flow through said central flow means of said tubular member, ignition means for igniting the fuel in said tubular member and means for suspending said tubular member in a well.

2. The apparatus of claim 1 further characterized in that the refractory tubular lining comprises tubular graphite having a wall thickness of at least 1/2 inch.

3. The apparatus of claim 1 further characterized in that the fuel means is charcoal.

4. The apparatus of claim 3 further characterized in that the charcoal is oil soaked.

5. The apparatus of claim 1 further characterized in that the port means are sized so as to bypass from 2 to 5 times the amount of air that flows through the fuel means in said central iiow path.

6. The apparatus of claim 1 further characterized in that the ignition means comprises an incendiary means and a timing device for remotely igniting said incendiary means.

7. The method of igniting an oil-bearing formation penetrated by a well and having a perforated well liner adjacent said formation comprising the steps of inserting into a well a container of particulate fuel, lowering said container to a position at least partially adjacent an oilbearing formation to form an annular chamber between the lower portion of said container and the perforated well liner adjacent said formation, providing a ow restriction in said annular chamber above said perforated portion of said well liner, injecting oxygen containing gas into said well and flowing said oxygen containing gas down said well to a position above said container, passing a portion of said oxygen containing gas through said fuel in said container, by passing an amount of oxygen containing gas from 2 to 5 times the amount that flows through said fuel to said annulus below said flow restriction and flowing said bypass oxygen containing gas through said annulus, igniting the fuel in said container and continuing to inject oxygen containing gas down said well and dividing said oxygen containing gas between said fuel and said annulus in a ratio of 1 to 2:5 to burn said fuel to ignite said oil-bearing formation.

References Cited UNITED STATES PATENTS 2,286,075 6/1942 Evans 166-58 2,500,990 3/1950 Higginbotham et al. 166-58 2,941,595 6/1960 Emery 166-39 X 2,997,105 8/1961 Campion et al. 166-59 3,044,551 7/1962 Pryor 166-59 3,072,184 1/1963 Parker 166-39 X 3,072,190 1/1963 Reichle 166-58 X 3,076,505 2/1963 Pryor 166-58 X 3,322,195 5/1967 Brown et al 166-39 X 3,323,591 6/1967 Harvey 166-58 X STEPHEN I. NOVOSAD, Primary Examiner. 

1. AN APPARATUS FOR USE IN IGNITING AN UNDERGROUND PETROLEUM-BEARING FORMATION PENETRATED BY A WELL, SAID APPARATUS COMPRISING AN OUTER TUBULAR MEMBER, A REFRACTORY TUBULAR LINING ON THE INTERIOR OF AT LEAST A SUBSTANTIAL PORTION OF SAID TUBULAR MEMBER, SAID REFRACTORY LINING FORMING A CENTRAL FLOW PATH THROUGH SAID TUBULAR MEMBER, FUEL MEANS CONTAINED IN SAID CENTRAL FLOW PATH ADJACENT THE PORTION OF SAID TUBULAR MEMBER HAVING SAID REFRACTORY TUBULAR LINING, SAID FUEL MEANS BEING ARRANGED TO ALLOW THE PASSAGE OF A SUBSTANTIAL AMOUNT OF AIR THERETHROUGH, MEANS ON THE LOWER END OF SID TUBULAR MEMBER ALOWING PASSAE OF AIR THROUGH THE OTTOM END OF SAID TUBULAR MEMBER, PORT MEANS FORMED IN THE UPPER PORTION OF SAID TUBULAR MEMBER ABOVE SAID FUEL MEANS PROVIDING COMMUNICATION BETWEEN THE CENTRAL FLOW PATH OF SAID TUBULAR MEMBER AND THE OUTSIDE OF SAID TUBULAR MEMBER TO PROVIDE BYPASS AIR TO THE OUTSIDE OF SAID TUBULAR MEMBER, FLOW RESTRICTION MEANS ON THE OUTSIDE OF SAID TUBULAR MEMBER ABOVE SAID PORT MEANS AND ADAPTED TO FORM A FLOW IMPEDANCE BETWEEN THE OUTSIDE OF SAID TUBULAR MEMBER AND A WELL CASING TO CAUSE A SUBSTANTIAL AMOUNT OF AIR TO FLOW THROUGH SAID CENTRAL FLOW MEANS OF SAID TUBULAR MEMBER, IGNITION MEANS FOR IGNITING THE FUEL IN SAID TUBULAR MEMBER AND MEANS FOR SUSPENDING SAID TUBULAR MEMBER IN A WELL.
 7. THE METHOD OF IGNITING AN OIL-BEARING FORMATION PENETRATED BY A WELL AND HAVING A PERFORAED WELL LINER ADJACENT SAID FORMATION COMPRISING THE STEPS OF INSERTING INTO A WELL CONTAINER OF PARTICULATE FUEL, LOWERING SAID CONTAINTER TO A PORSITON AT LEAST PARTIALLY ADJACENT AN OILBEARING FORMATION TO FORM AN ANNULAR CHAMBER BETWEEN THE LOWER PORTION OF SAID CONTAINER AND THE PERFORATED WELL LINER ADJACENT SAID FORMATION, PROVIDING A FLOW RESTRICTION IN SAID ANNULAR CHAMBER ABOVE SAID PERFORATED PORTION OF SAID WELL LINER, INJECTING OXYGEN CONTAINING GAS DOWN SAID WELL TO A POSITION ABOVE SAID CONTAINER, PASSING A PORTION OF SAID OXYGEN CONTAING GAS TROUGH SAID FUEL IN SAID CONTAINER, BY PASSING AN AMOUNT OF OXYGEN CONTAINING GAS FROM 2 TO 5 TIMES THE AMOUNT THAT FLOWS THROUGH SAID FUEL TO SAID ANNULUS BELOW SAID FLOW RESTRICTION AND FLOWING SAID BYPASS OXYGEN CONTIANING GAS THROUGH SAID ANNULUS, IGNITING THE FUEL IN SAID CONTAINER AND CONTINUING TO INJECT OXYGEN CONTAINIG GAS DOWN SAID WELL AND DIVIDING SAID OXYGEN CONTAINING GAS BETWEEN SAID FUEL AND SAID ANNULUS IN A RATIO OF 1 TO 2:5 TO BURN SAID FUEL TO IGNITE SAID OIL-BEARING FORMATION. 